Friction bolster spring



paratively stiff helical springs.

Patented Nov. 25, 1941 UNITED STATES PATENT OFFICE FRICTION BOLSTER SPRING Herbert E. Tucker, Chicago, 111., assignor to James R. Cardwell, Chicago, 111.

Application December 18, 1939, Serial No. 309,775

9 Claims.

This invention relates to bolster supporting resilient units and more particularly to the type. v having frictional resistance to the compression Another object of the invention is the provision of a spring or resilient unit provided with rubber material that is adapted to be compressed, placed under shear, and caused to frictionally engage a metal surface for resisting the compression of the unit.

A still further object of the invention is the provision of a friction resilient unit that is simple in construction, easily assembled, composed of a minimum number of parts, and that is efficient and economical in operation.

Another object of the invention is the provision of a new and improved resilient friction unit that will have considerable deflection, ap-

proximately a constant deflection, for light as will as heavy loads; that is, it is adapted to properly resiliently support the car whether the same be lightly or heavily loaded, and that will absorb a great amount of sound and other mechanical vibrations incident to the travel of the car on the rails which would otherwise be transmitted to the car body.

Other and further objects and advantages of the invention will appear from the following description, taken in connection with the accompanying drawings, in which-- Fig. l is a side elevation of a railway truck, with parts broken away and showing the invention in position therein;

Fig. 2 is a vertical. section of the resilient unit in expanded position; 1

Fig. 3 is a similar section but showing the unit in compressed position;

Fig. 4 is a .section on the line 4-4 of Fig. 2;

Fig. 5 is a vertical section of a modified form of unit showing the same in expanded position;

Fig. 6 is a similar view showing the unitin compressed position;

Fig. 7 is a section on the line of Fig. 5; and

Fig. 8 is a perspective and friction shoes.

In resilient supports for railway cars, it is common practice to employ an assembly of comview of the resilient block must be stiff in order to have sufficient capacity for supporting the maximum loads. As a result of such construction, there is very little deflection for light loads. Furthermore, the helical springs being'free acting, harmonic vibration is not uncommon during the travel of the car under certain conditions.

The present invention seeks to remedy these conditions by providing a resilient friction unit that may be substituted for one of the helical springs whereby light loads will be much more resiliently supported than by the conventional spring assembly and that will prevent objectionable harmonic action of the assembly.

Referring now to the drawings, the reference character It designates a railway truck having the side frame H provided with a bolster opening 12 for receiving an end of the bolster I3, as is usual in such constructions. The bolster is supported by a spring assembly [4 within an enlargement l5 of the opening I2.

The spring assembly It comprises a plurality of helical bolster supporting springs IB and one or more friction spring units H. The helical spring I6 is' of the usual or any well known con-- struction and it is not thought necessary to further illustrate ordescribe the same.

The resilient friction unit IT, in the form of the device shown in Figs. 2, 3 and 4, comprises a pair of followers 118 and H which are arranged opposite each other.

In the form of the construction selected to illustrate one embodiment ofthe invention, the follower it is in the form of a casing it which, for the purpose of illustration, may be circularin cross-section, as shown in Fig. i. For convenience of description, the follower it may be designated the cylinder follower and the follower at, which is adapted to telescope within the follower it, may be designated the plunger follower.

ihe follower i8 is hollow or tubular with smooth inner friction walls. It has an outer end wall which has a boss or extension extending axially inwardly from its central portion. This boss has an opening 22 extending axially of the follower. The inner end of the follower is open. If desired, the thickness of the metal may be increased to form circumferential bands 23 and 24 at the ends and one or more bands at the intermediate portions as at 25 for resisting the expansive force of the rubber upon compression of the unit, aswill presently appear.

The follower I9 is in the form of a plunger These springs having its inner end 26 reduced to form a shoulder or flange 2'! which limits the inward movement of the plunger during the compression of the unit. The follower or plunger I9 may be, and preferably is, cored to lighten the structure as indicated at 28. This follower is also provided with an axial depression 29 and with an axial opening 3| through its inner wall 32.

' inner surface of the casing and engages said casing. A portion of the rubber is removed from the inner end of the rubber to form a conical expansion space 31 in the axis of the casing.

If desired, the follower l9 may be provided with a boss'30that is received in the recess 31 for positioning the rubber block on the follower. A portion of the rubber at the inner peripheral edge of the block is removed to form an annular expansion space 38 for the rubber which space may be triangular in cross-section. The plungers are held in normal contact with the block by I a bolt 39 which extends throughthe alined openings 22 and 3| of the follower members. A nut 4| on the bolt is adapted to prevent separation of the parts and, if desired, the nut may be adjusted on the bolt for placing the rubber block under a slight initial compression.

In the operation of the device, when the unit is compressed, the casing 20 will be moved downwardly over the plunger 26 thereby compressing the rubber block and simultaneously distorting the same into the expansion spaces 35, 31 and 38, as shown in Fig. 3.

There will be no relative sliding movement between therubber block and follower casing 20 during compression of the rubber until the space 38'has been filled with the distorted rubber and, consequently, the initial compression meets with far less resistance than the final compression.-

As a result of this arrangement, the light loads will be more resiliently supported than the conventional helical bolster supporting spring assembly and yet the capacity for heavy loads will remain substantially the same. In other words, with the present assembly, light loads will be supported with approximately the same resilient movement as the heavier loads. Furthermore, the rubber will absorb a great amount of sound and other vibrations which would otherwise be transmitted to the car and this is very important where. the-unit is employed on passenger cars and especially on high speed passenger trains.

During the compression of the unit, the follower casing I8 will be forced to pass the rubber block which frictionally engages the walls of this follower thereby placing the rubber under more or less shear. As the rubber is compressed, more and more of it will be forced into contact with of construction in which friction shoes are interposed between portions of the rubber block and the inner wall of the casing follower. Since the casing follower l8 and the plunger follower l9 are substantially the same as that described in Figs. 1 to '4, it is not thought necessary to rebeat the description of these parts. The plunger casing l9 telescopes within the follower casing H3 in a manner already described.

A resilient block 42, which may be of rubber or the like, is interposed between the followers and comprises an upper reduced portion 43 which engages the depression 2| of the casing, as in the previous construction. The inner end of the block 43 has a conical shaped opening 44 which forms an expansion space similar to the space 31 in Fig. 2. The lower end of the block 42 fits about the boss 30 of the plunger follower IQ for positioning the same as n the previous construction.

Interposed between the lower enlarged end portion of the rubber block 42 are a plurality of friction shoes 45, four being shown, Fig. 8, which are seated in recesses 46 formed in the rubber so that the outer surface of the shoes will be substantially flush with the peripheral surface of the blocks. Each of these shoes-is provided with projections 41 on their inner ends which extend laterally inwardly and are seated in corresponding recesses 48 formed in the periphery of the rubber block. The rubber block is preferably vulcanized to these shoes so that the shoes will not become displaced when the unit is compressed and released. The shoes are spaced apart a substantial distance so that theperipheral surface of the rubber between the shoes will frictionally engage the inner surface of the follower casing and add materially to the frictional resistance to the compression of the unit.

When the unit is compressed, the friction between the shoes and the follower and between the rubber and the follower will resist such compression. f

While the rubber block, as shown, is of a particular form, it is understood that various other forms may be used, it being only necessary to provide space within one or both followers for the inner surface of the wall 20; that is, the fricl8 engages the flangeor stop 21, the unit will function as a solid column for preventing further compression of the rubber unit.

In Figs. 5, 6, 7 and 8 is shown a modified form the distortion of the rubber since rubber is almost incompressible.

It is thought from the foregoing, taken in connection with the accompanying drawings, that the construction and operation of my device will be apparent to those skilled in the art and that changes in size, shape, proportion and detail may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A resilient unitfor a-spring assembly for use in railway cars comprising a pair of telescopic followers, one of said followers being hollow and having a closed end provided with an inwardly extending .axial boss, a rubber block having a reduced upper end engaging said boss .and having a portion of its opposite end frictionally engaging the walls of said hollow follower, and the other of saidfollowers having a portion slidably within the hollow follower and seated against said rubber block whereby upon initial compression of said unit, said block will be compressed and upon further compression, said rubber block will be caused to frictionally engage the hollow follower.

2. A resilient unit comprising a cup-shaped follower, a second follower having a closed end telescoping in the open end of the first-named :ollower, said cup-shaped follower having an inwardly extending boss in its bottom wall of ma-. terially less diameter than the interior diameter of the cup-shaped iollowerja block of rubber having its upper and lower ends reduced and engaging said boss and second follower end and adapted to have its intermediate portion compressed into frictional engagement with the inner walls of the first-named follower for frictionally resisting the compression of said unit.

3. In a railway truck, a resilient friction unit comprising a pair of relatively movable elements adapted to slide along each other, one of said elements having arigidwall provided with a friction surface, and rubber and metal means both frictionally engaging said surface, said rubber being distortable without relative movement between said metal means and element during the initial compression of said unit, but upon final compression movement said metal means being slidable aiong said friction surface for resisting the' compression of said unit.

4. A resilient unit comprising a follower 'hav-,

ing an enlarged recess therein defined by a rigid side wall and an outer end wall, said follower having its inner end open, a rubber block face. of said side wall adjacent to the open end of said follower and having a reduced axial extension normally spaced radially inwardly from 5. A resilient, friction unit comprising a follower provided with a recess therein and havtact with. the inner surface of said side wall, andfor causing the side wall engaging portion of said block to slide along said follower when said unit is compressed for tirictionally .resisting the compression of said uni A V '7. A resilient friction unit comprising opposed relatively movable elements, at least one of said elements being in the form of a tubular casing having its inner end open and having its outer end wall provided with an axial inwardly extending boss forming a recess surrounding said boss within said casing,- a rubber block having its inner end engaging the side walls of said casing adjacent its open end and having its outer end reduced and seated against said boss, the other follower telescoping within the inner end of said casing whereby when said unit is compressed said rubber block will frictionally engage said walls and will'be so distorted upon of less cubical dimension than said recess mounted within said recessandengaging the inner surthe compression of said unit that a portion of said block will be forced into contact with said wall and a portion will be distorted into said recess.

8. A resilient friction unit for use in railway trucks comprising a pair of followers, at least one of said followers being hollow with rigid side walls, an end wall for the outer end of said hollow follower, the inner end thereof being open, a boss on'the central portion of said end wall ing rigid .side and end walls defining said recess,

the inner end of,said recess being open, a single rubber block within said recess and engaging the bottom wall of said recess and having its inner end frictionally engaging the inner end of said side wall adjacent to the open endof said follower and having a portion of materially less cross-sectional area'than said recess, a second vfollower engaging said block for compressing the same into frictional engagement with the and extending inwardly therefrom a substantial distance forming a recess around said boss, a single rubberblock interposed between said followers and within said, hollow follower, the inner end portion of said block engaging said side wall and having a conical recess extending axially into its inner end, the outer end of said block bei'ng tapered outwardly from its central portion to a diameter substantially equal to that of said boss and seated on said boss, said block being distortable into said recess during maxi-" mum compression, the form of the block including the taper being such that the unit has approximately a constant deflection for all loads and upon compression beyond a predetermined w amount will have a frictional engagement .with said rigid walls throughout its follower contacting surface during the compression of the unit. 9. A resilient friction unit for use in railway trucks comprising a pair of opposed followers, one of said followers having a tubular side wall and an outer end wall, the other of said followsaid side wall and for causing the entire side wall engaging portion of said block to slide along said side wall when said unit is compressed".

6. A resilient friction unit comprising a cylindrical casing having its outer end closed by an end .wall and having an inwardly extending rigid side wall, a single rubber block mounted in said casing within said side wall and having its outer 'end reducedmaterially and in contact with the central portion of the end wall of said casing and having its inner end frietionally engaging said casing adjacent its openend, and a plunger follower eng'" ing the inner end or said block for com-pressing said block into frictional coners telescoping the one follower, a rubber block seated on said other follower and having its inner end engaging said sidewall throughout its circumferential extent and frictionally slidable along said wall for resisting the compression of said unit, said rubber block having a material portion restricted in cross-section and spaced from said side wall a material distance when said unit is expanded but engaging said end wall and distortable into contactwith said side-wall when said unit iscompressed, said block being of such'formation that the unit will have a substantially constant deflection for variable loads.

HERBERT E. TUCKER. 

